SPID#: 45 This study has three objectives (1) mapping oxytocin and vasopressin receptors in the rhesus monkey brain, (2) investigating the release of oxytocin and vasopressin in the monkey brain, and (3) describing the behavioral and cognitive effects of oxytocin and vasopressin. Oxytocin and vasopressin are neuropeptides that have been previously implicated in complex social behaviors in rodents. These studies will extend much of this earlier work to non-human primates preparatory to investigating oxytocin and vasopressin in selective neuropsychiatric disorders such as schizophrenia and autism. In the first year of this study, we have mapped oxytocin and vasopressin receptors in four rhesus monkey brains using receptor autoradiography and we have cloned and sequenced receptors for both neuropeptides. The distribution of vasopressin receptors is markedly different than previously reported from maps of rodent brains. The binding of a putative selective oxytocin receptor ligand appears to overlap the vasopressin receptor pattern and studies using RT-PCR followed by Southern blotting have demonstrated that much of this binding is indeed for the V1a receptor rather than the oxytocin receptor. In the coming year we plan to pursue these neuroanatomic studies further to determine if the rhesus monkey brain contains an oxytocin receptor. In addition, we plan to initiate in vivo microdialysis studies to measure oxytocin and vasopressin release from limbic sites. Finally, we hope to begin administering both peptides to both adult and infant monkeys to determine functional roles for these hormones in the macaque brain.